The boiler in the heat power plant produces the flue gas entraining sulfur oxides due to combustion of fossil fuel. Among the sulfur oxides, specifically sulfur dioxide and sulfur trioxide are ones of primary causes in environmental concerns such as air pollution and acid rain. Thus, the heat power plant is provided with a desulfurizer to desulfurize sulfur oxides such as sulfur dioxide and sulfur trioxide in the flue gas.
Prevailing desulfurizers are wet ones using limestone-gypsum process; especially spray-type ones are employed frequency. In the spray-type desulfurizer, absorbing liquid containing a wet desulfurizing agent is sprayed to the flue gas in an absorbing column where sulfur oxides in the flue gas are desulfurized by the absorbing liquid. In the desulfurizer, the longer the time during which the sulfur oxides are in gas-liquid contact with the absorbing liquid (hereinafter referred to as reaction time) is, the more the desulfurization performance is enhanced. Thus, it may be conceived that the absorbing column is increased in height to elongate the reaction time. However, the desulfurizer with the absorbing column increased in height has a problem that construction cost is increased.
Then, a simplified desulfurizer has been proposed which can elongate a reaction time while suppressing height of an absorbing column. The simplified desulfurizer shown in undermentioned Patent Literature 1 comprises a V-shaped reactor vessel arranged below a flue path connecting a boiler with a stack to extract from the flue path part of flue gas flowing therethrough and return the same to the flue path, a nozzle arranged on an inlet side of the reactor vessel to spray absorbing liquid in a direction same as that of flue gas flow and a reservoir arranged at a bottom of the reactor vessel to capture the absorbing liquid, thereby attaining simplification in structure in comparison with conventional desulfurizers.
Undermentioned Patent Literature 2 discloses that, in a wet flue-gas desulfurizer with an exhaust gas flow passage for horizontally guiding exhaust gas, a plurality of sprayer nozzles are arranged along the exhaust gas flow passage to enhance desulfurization performance by differentiating pressures, injection angles, flow rates of the respective spray nozzles. Undermentioned Patent Literature 3 discloses that, in a wet flue-gas desulfurizer with an exhaust gas flow passage for horizontally guiding exhaust gas, a plurality of sprayer nozzles are arranged along and vertically of the exhaust gas flow passage to minimize ranges with no spray drops to thereby enhance desulfurization performance.